Carburetor pump



Nov. 29, 1955 o. c. KELLER CARBURETOR PUMP Filed Feb. 11, 1953 IN VEN TOR. ORV/4L! C. A? :2

United States. Patent CARBURETOR PUMP Orville C. Keller, Detroit, Mich.

Application February 11, 1-953, Serial No. 336,255

4 Claims. (Cl. 309-47) The present invention relates to an improved piston and connecting rod assembly, and more particularly to such an assembly, which is principally but not exclusively adapted for use in the accelerating system of a carburetor.

In order to. better understand the present invention it is believed a brief description of the prior art devices will be helpful. In a conventional carburetor the accelerating pump is connected to the throttle linkage, and its function is to enrich the fuel mixture to the engine temporarily for rapid acceleration. The fuel is drawn into the pump chamber, through a pump inlet passage and through a suitable inlet ball check valve on the upward stroke of the pump piston. When the throttle is opened, the piston moves downward closing the pump check valve and overcoming the weight of the pump discharge needle valve. The accelerating fuel then goes around this valve and out the pump discharge jet to provide the enriched mixture.

A spring, between the operating rod and the, pump piston stem, allows the pump operating rod to overrun the pump piston when the throttle is opened suddenly. This overrun causes the pump piston to be subjected to the pressure of the spring thereby giving a prolonged steady discharge of the accelerating fuel.

The industry is continuously strivingto improve the operation of the accelerating pump so that the optimum smooth travel of the pump piston is obtained when the spring is unloaded, thereby giving a uniform discharge of accelerating fuel. At the same time it is seeking to develop a pump piston which has the best wear resisting characteristics so that a long life of desirable pump action is assured, and one that can be economically produced. Bearing in mind that a single manufacturer of automobiles may use a million or more of these pump pistons annually, it can be readily appreciated that even a small saving per unit will become a very large saving when considered in terms of an annual production.

Among the conventional types of pump pistons used heretofore are those having leather or other flexible material forming their side walls so as to provide a seal which will prevent leakage past the pump pistons when they are reciprocated. The pistons generally have had a relatively rigid connection with the piston stem, and these assemblies have been effective in use, although they have not proved to have as long a life and as efiicient operation as is desired. Among the shortcomings attributed to these assemblies is that the seal is not always as effective as it should be and in certain instances the leather has been worn away too readily. Thus, the desired steady uniform discharge of fuel for acceleration purposes has not been provided. Also servicing and maintenance costs have been higher than desired.

Efiorts have been made to overcome these shortcomings by providing a less rigid assembly, but the desired degree of success has not been achieved. One such eifort has consisted in providing a universal connection 2,725,267 Patented Nov..29, 1955.

in the piston stem near the piston. Such an assembly has proved to be more costly to produce, and it has not made possible an operation which will provide the optimum results in terms of long life and serviceability.

With the foregoing premises in mind, it is the principal object of the present invention to provide an improved piston and stem assembly for use in the accelerating pumpof a carburetor, said assembly being constructed and arranged to effect optimum performance at a minimum cost of construction and servicing.

It is another object of the present invention to provide an improved piston and. stem assembly of the foregoing character in which a universal connection. is made between the piston and the stem so that misalignments of the stem will be more readily accommodated than has heretofore been possible, thereby assuring a more uniform, smooth discharge of accelerating fuel when the pump spring isv being unloaded and substantially eliminating uneven wear of the flexible piston side wall.

Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

in the drawings:

Fig. l is a fragmentary section of a carburetor showing the piston and piston stem assemblyembodying the present invention incorporated inthe accelerator pump; and

Fig. 2' is'an enlarged view of the piston and piston stem assembly illustrating the. universal connection between these associated parts.

Before explaining the present invention in detail, it is. to be. understood that the invention is not limited in its application. to. the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is. totbe understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Referring now to the drawings a more detailed description ofthe. invention will be given. The accelerat ing pump 10- has a pump chamber 12 into which fuel is adapted to be drawn'through the pump inlet passage 14 ball. check valve 16: onthe upward stroke of the pump piston 18. When the throttle (not shown) is opened, the piston 18 can move downward closing the check valve 16 discharging fuel through the passage 20.

A spring 22 is operatively mounted between the operating rod 24 and the piston 12 so that when the throttle (not shown) is opened wide the rod 24 can overrun the piston 18 by virtue of the elongated slot 26 formed in the piston stem 28, and the spring 22 will then exert pressure on the piston 18 causing it to move downwardly at a rate governed by the rate of displacement of the fuel from the chamber 12 through the passage 20. The general construction and arrangement of the accelerat ing pump 10 is old in the art, and it should be understood that the present invention is not limited to use with this particular pump, but may be used with other accelerating pumps of this general character.

Referring to Fig. 2, the novel features of the present invention can be seen. The piston 18 has a body portion 30 which has an annular groove 32 around its periphery. A flexible member 34, preferably formed of leather overlaps the sides of the body portion 30 and a piston expander spring 36 is seated in the groove 32 and operates to expand the flexible member 34 into sealing engagement with the side Walls of chamber 12, Fig. l.

The lower end of the piston stem 28 has a reduced portion 38 on which a collar 40 is held by the retaining ring 42 which is press fitted onto the portion 38. Clearance is provided between the outer circumference of ring 42 and the inner circumference of the depending sleeve 44 of collar 49. There is also clearance between the upper end of ring 42 and the lower side of collar 40.

The piston 13 is attached to the stem 28 by press fitting the body portion 36 over the sleeve 44 and this also retains the flexible member 34 in place since it. will be clamped between collar 40 and body portion 30. When the piston 12 and the stem 28 are assembled in this manner a universal as well as a swivel connection is provided.

One of the important features of the present invention is that the universal connection is located within the piston 12 so that the latter can more easily accommodate misalignment of the stem 28 during the pumping stroke of the accelerating pump. This assures more uniform and even wear of the leather member 34, and also eliminates irregular pumping action which may be caused if leakage occurs past the piston 12 on its pumping stroke. This leakage can occur if the piston 18 is reciprocated for any length of time while not properly aligned.

Another feature of the present invention is its simplicity of construction and the ease with which it can be assembled with a minimum of simply constructed parts so that its. initial cost will be relatively low.

Having thus described my invention, I claim:

1. In a carburetor accelerating pump, a piston and connecting rod assembly comprising a connecting rod having a reduced end portion, and a piston having a cylindrical body portion with a concave groove around its periphery and an opening in one end, an expander spring in said groove, a leather sleeve overlying said one end of the body portion and encircling the latter and said spring, a collar with a depending sleeve fitted into the opening in the one end of said body portion, said collar having a throat through which the reduced portion of the rod extends and .an overlapping lip which holds the overlying sleeve portion against said body portion, and a retainer ring on said reduced end portion of the rod for preventing withdrawing the rod from said collar, said end portion and ring having a limited radial clearance with said sleeve portion to permit universal movement of the rod relative to the piston.

2. In a carburetor accelerating pump, a piston and a connecting rod assembly comprising a connecting rod 45 having a reduced end portion, and a piston having a cylindricalbody portion with an opening in one end, a collar with a depending sleeve press fitted into the opening in the one end of said body portion, said collar having a throat through which the reduced portion of the rod extends, and a retainer ring on said reduced end portion preventing withdrawing the rod from said collar, said end portion and ring having a limited radial clearance with said sleeve portion to permit universal movement of the rod relative to the piston.

3. In combination in a carburetor accelerating pump, a piston and connecting rod assembly comprising a connecting rod having a reduced end portion, and a piston having a cylindrical body portion with an opening in one end, a collar with a depending sleeve fitted into the opening in the one end of said body portion, said collar having an annular groove on its upper surface and a throat through which the reduced portion of the rod extends, and a retainer ring on said reduced end portion preventing removal of the rod from said collar, said end portion and ring having a limited radial clearance with said sleeve portion to permit universal movement of the rod relative to the piston, the other end of said rod having an elongated slot through which an actuating rod can be passed, a spring retainer carried in said slot, and a coil spring mounted in compression between said spring retainer and the grooved portion of said collar.

4. An article of manufacture for use in a carburetor accelerating pump comprising a connecting rod having a reduced portion at one end and an elongated slot in the other end, and a piston having a cylindrical body portion with a concave groove around its periphery and an opening in one end, an expander spring in said groove, a leather sleeve overlying said one end of the body portion and encircling the latter and said spring, a collar with a depending sleeve fitted into the opening in one end of said body portion, said collar having a throat through which the reduced portion of the rod extends and an overlapping lip which holds the overlying sleeve portion against said body portion, and a retainer ring on said reduced end portion of the rod for preventing withdrawing the rod from said collar, said end portion and ring having a limited radial clearance with said sleeve portion to permit universal movement of the rod relative to the piston.

References Cited in the file of this patent UNITED STATES PATENTS 577,957 Herron Mar. 2, 1897 1,606,511 Carson Nov. 9, 1926 1,946,715 Shield Feb. 13, 1934 fr v... 

